Longitudinal seat adjustment device, especially in a motor vehicle

ABSTRACT

The invention relates to a longitudinal seat adjustment device comprising an upper rail ( 40 ) and a lower rail ( 10 ). The upper rail ( 40 ) sits in the lower rail ( 10 ). Between the two rails ( 10, 40 ) a spindle ( 14 ) is fixedly connected to the lower rail ( 10 ). Drivable on said spindle ( 14 ) is a transmission ( 30 ), which can be retained in a specific manner by means of slotted bridges in the case of a crash.

[0001] The invention relates to a longitudinal seat adjustment device,especially in a motor vehicle, according to the features of the preambleof claim 1.

[0002] Such longitudinal seat adjustments have now become sufficientlywell known. Longitudinal seat adjustments have a lower rail fixed to achassis, inside which lower rail an upper rail, to which the seat isattached, can be propelled by motor. Here a spindle fixed by itsrespective ends to the lower rail sits inside the upper rail, on whichspindle a transmission fixedly coupled to the upper rail is arranged inaxially movable fashion. The seat, which is located on the two upperrails arranged parallel to one another, can be propelled via a motordevice that sits between the rails.

[0003] Examples of devices for the purpose of longitudinal seatadjustments have been disclosed in DE 36 40 197 A1, DE 42 08 948 C2, DE196 42 655 C2, DE 198 15 283 A1, DE 198 44 817 A1, DE 199 44 690 A1, andWO 95/16 585. The goal of the invention is to identify a compactlongitudinal seat adjusting device in which only a few components areneeded and that can without difficulty accommodate the forces that occurespecially in the case of a crash. Here the transmission to bediscovered for the longitudinal adjustment of the seat is to transformthe rotational motion of the drive motor into a translational motion.

[0004] A further goal of the present invention is for the space occupiedby the longitudinal seat adjusting device to be relatively small,preferably only 15 mm in width. Moreover, the permissible protrusion ofthe upper rail is likewise not to be too great, at most some 15 mm.Finally, the device according to the invention is to satisfy a strengthrequirement in both directions, which is for example 25000 N. Finally,the device according to the invention is to be relatively rapidlyadjustable, that is, for example at between 15 and 25 mm/s over arelatively long adjustment range of for example 300 mm.

[0005] This object is achieved by a device having the features of claim1 and/or a device having the features of claim 2.

[0006] Developments of the invention are the subject of the dependentclaims referred hereto.

[0007] In a preferred embodiment of the invention, the rotational motionof the motor is transformed to the translational motion via a flexibleshaft, a worm, a spindle, and a spindle nut.

[0008] In order to reduce noise it is recommended that the spindlepreferably be aligned exactly parallel to the upper rail and lower rail.

[0009] In another development of the invention, at least one of the wallparts of the upper rail is provided with a notch through which aflexible shaft coupled to a drive motor is guided.

[0010] In a further development of the invention, side walls of theupper rail are formed as slotted bridges and pressed into the interiorof the upper rail, the transmission housing being able to be bracedagainst these slotted bridges.

[0011] The transmission housing preferably includes two housing shellsmade of plastic, which are connected to one another by ultrasonicwelding. The housing, which is connected by ultrasonic welding of thetwo housing halves, is advantageously designed only for compressiveloading.

[0012] A clamping holding of the transmission is achieved according tothe invention by metal stirrups bent into an L shape oppositely workedinto a recess of the upper rail, between which stirrups the transmissionhousing is slipped with wall tapers.

[0013] The spindle nut and the above-mentioned thrust ring, which canbrace itself in walls of the upper rail in the case of a crash, arepreferably formed integrally or in one piece. Both are preferably madeof metal.

[0014] In another development, a worm seam is coaxially applied to thespindle nut by plastic injection.

[0015] The longitudinal seat adjustment functions as follows. Thetransmission is built into a U-shaped seat rail. This seat rail iscomprised of a lower rail and an upper rail, as referred to above. Thelower rail is connected to the body of the vehicle, while the upper railis connected to the vehicle seat. The transmission housing is fixated onthe upper rail via two lugs and is preferably secured with a dowel pin.The spindle nut itself is connected to the lower rail via two screws.The seat is adjusted via the translational motion of the spindle/spindlenut pair. Two rails and thus two transmissions (one left and one right)are required for the adjustment of one seat.

[0016] The principal function of the transmission includes transformingthe rotational motion into a translational motion. The rotational motionis transmitted to the transmission by a motor and the adapted flexibleshaft via a square integrated into the transmission worm. The spindle isdriven via the injection-coated worm gear with a well-definedtransmission ratio. The transformation to translational motion iseffected via the spindle/spindle nut pair. A trapezoidal thread isavailable to both parts.

[0017] The transmission according to the invention is distinguished inparticular by the fact that it can withstand very high forces in thecase of a crash. The housing of the transmission is not itself capableof withstanding the forces in the case of a frontal crash. Such forcesare around 24000 N. In the transmission according to the invention, thehousing of the transmission is destroyed in the case of a crash and thethrust ring, which is preferably made of metal, can push against thecontact surfaces of the upper rail on both sides. The parts upper rail,thrust ring, spindle, spindle nut and lower rail in the longitudinalseat adjustment device according to the invention are situated in theforce transmission path in the case of a crash and can advantageouslywithstand the crash forces.

[0018] The longitudinal seat adjustment device according to theinvention is distinguished by the free positionability of thetransmission on the rail, the integral forming of the thrustring/spindle nut, a rotating nut, and a rotating spindle. Moreover, alarger travel distance results with the device according to theinvention under the same installation conditions.

[0019] Moreover, the device according to the invention, or thetransmission implemented therein, is distinguished by the followingfeatures.

[0020] The geared adjustment drive is composed of only four or fivecomponents. The gearing parts of the worm transmission are directlysupported in a plastic cage. Separate support components can bedispensed with. The cage constituents are connected and fixated byultrasonic welding via an individual lowering path with an eye tolash-free functioning of the gearing parts. The flexible shaftattachment is an integral constituent of the fixation of thetransmission to the seat rail. The flexible shaft attachment provides acoaxial fixation of the rotating flexible shaft to the drive worm and ispreferably fastened to the plastic cage via a bayonet connection withsnap closure.

[0021] The transmission cage is connected to the seat rail in alash-free but elastic manner via slotted bridges and rimmed holes insheet metal and can be individually adapted in the assembly process. Thespindle nut is simultaneously the worm gear and the thrust ring. Theintegrated thrust ring relieves the plastic transmission of crash forcesin the case of a crash. The thrust ring here braces itself by projectionon notches made in the seat rail. The threaded spindle can be removedsubsequently for purposes of assembly and repair.

[0022] In what follows, the device for the purpose of longitudinal seatadjustment according to the invention will be explained in greaterdetail on the basis of an exemplary embodiment with a plurality ofdrawings, in which

[0023]FIG. 1 is a perspective depiction of the lower rail with spindleinstalled and with transmission sitting on the spindle, in overhead viewin perspective depiction,

[0024]FIG. 2 is a perspective depiction of the rail of FIG. 1 withinserted upper rail or seat rail,

[0025]FIG. 3 is a detail depiction of the transmission held in the upperrail,

[0026]FIG. 4 is an end-on view of the arrangement depicted in FIG. 2 andFIG. 3 in end-on view,

[0027]FIG. 5 shows exemplary dimensional information on the traveldistance of the upper rail relative to the lower rail in mm,

[0028]FIG. 6 is a detail view of the end stop overlap,

[0029]FIG. 7 shows the seat rail section in the transmission region,

[0030]FIG. 8 shows the upper rail with opened housing,

[0031]FIG. 9 is a detail depiction of the fastening of the transmissionto the lower rail,

[0032]FIG. 10 shows a proposal for an assembly sequence for the deviceaccording to the invention,

[0033]FIG. 11 shows the region of the transmission on an enlarged scale,

[0034]FIG. 12 shows the transmission in exploded view,

[0035]FIG. 13 is a detail view of the flexible shaft adapter, and

[0036]FIG. 14 presents detail views to explain the accommodation ofcrash forces with the device according to the invention.

[0037] As can be seen from FIG. 1, a spindle 14 sits inside a lower railwith an O-shaped cross section, which is fixed to the chassis of avehicle via mounting screws 12 at either end. This spindle 14 is fixedlyarranged in lower rail 10 at both its ends via an end stop 18. Theconnection between spindle 14 and lower rail 10 can be effected inarbitrary fashion. In the exemplary embodiment depicted, this spindle 14is fastened to the bottom of lower rail 10 via its end stops 18 withmounting rivets 16. There is an adjustment nut 20 at the upper end ofspindle 14, depicted at the left in FIG. 1, and there is a stop nut 22at the end depicted at the lower right. A transmission 30, explained indetail below, is propellably arranged on the spindle. Transmission 30 isdriven by a flexible shaft 50. When the flexible shaft rotates, thetransmission moves to the left or right on the spindle, depending on thedirection in which flexible shaft 50 turns.

[0038] An upper rail 40 is fixedly coupled to transmission 30. A seat,preferably a seat of a motor vehicle, is fastened to upper rail 40.Lower rail 10 together with upper rail 40 and transmission 30 arearranged parallel to one another under a seat to be adjusted. Betweeneach such pair of rails sits a drive motor, which drives the flexibleshaft 50 of each transmission 30 so that the seat can be moved towardthe front or toward the rear.

[0039] The seat of the transmission in upper rail 40 is depicted on anenlarged scale in FIG. 3. FIG. 7 gives a similar depiction, but viewedfrom the other side, with the lower rail omitted. In its upper wallpart, upper rail 40 has at its disposal a notch in which the box-shapedhousing of transmission 30 sits. Transmission 30 is clampingly held inthis notch 45. For this purpose, wall sections of the upper wall arebent inwardly by 90° into notch 45 and serve as stop lug 43. Two ofthese stop lugs 43 are situated oppositely in the longitudinal directionof upper rail 40. These stop lugs 43 can be seen especially clearly inFIG. 8. Moreover, the box-shaped housing of transmission 30 sits betweentwo wall sections 46 lying parallel to one another, which extendupwardly in parallel fashion integrally from the side walls of upperrail 40. Thus transmission 30, which is formed from a housing top 31 anda housing bottom 32 and is preferably made of plastic, sits between thetwo above-mentioned stop lugs 43 and wall sections 46. The wall section46 facing toward the observer is provided with a hole through whichflexible shaft 50 intrudes into the interior of the housing oftransmission 30.

[0040] Moreover, so-called slotted bridges 41 are pressed into the sidewalls of upper rail 40. These are wall sections that have been pressedinto the interior of upper rail 40 through slots, parallel to oneanother, made in the side walls of upper rail 40. Such slotted bridges41 are located in pairs directly opposite one another. These slottedbridges 41 constrict the interior space of upper rail 40 and serve(compare FIG. 9) as a stop for housing top 31 and housing bottom 32 oftransmission 30. Further, a notch 42, which lies between therespectively arranged slotted bridges 41, are located oppositely in thetwo sides of upper rail 40. This notch 42 serves for the partialaccommodation of a thrust ring 34 in a manner explained below.

[0041] Flexible shaft 50 projects into the interior of the housing oftransmission 30 via a flexible shaft adapter 52. A worm 35, which is inengagement with a spindle nut 36, sits in the interior of transmission30 at the end of this flexible shaft adapter 52. This spindle nut 36 isprovided with a worm gear. As can be seen particularly clearly from FIG.12 in particular, a thrust ring is integrally molded onto this spindlenut with worm gear. The spindle nut and the worm gear and thrust ringare preferably made of metal. In addition, there can also be a plainwasher 37 inside transmission 30. The housing of transmission 30,composed of housing bottom 32 and housing top 31, is made of plastic andhas box-shaped parts 31 a and 32 a through which spindle 14 is guided.The ends of these box-shaped parts 31 a and 32 a find their stop on theabove-mentioned slotted bridges 41. When the transmission is propelledby drive via flexible shaft 50, the upper rail is carried along thespindle and thus inside lower rail 10 by the totality of the arrangementof transmission and upper rail as described.

[0042] As FIG. 9 shows, slotted bridges 11 can also be made in thebottom wall of the lower rail. These slotted bridges 11 are likewisewall sections bent or impressed toward the upper rail, which wallsections, as FIG. 9 shows, are arranged oppositely to mounting rivets 16in front of respective end stops 18.

[0043] As the depiction of FIG. 9 shows clearly, in the case of a crashthe axial acceleration of the seat that occurs is intercepted both byslotted bridges 11 and 41 and also by the thrust ring in cooperationwith the notch in upper rail 40. Here slotted bridges 11 and 41 are ineach case arranged in pairs so as to ensure effective bracing of theadjustment device of the seat adjustment regardless of whether theacceleration is toward the front or the rear in the case of a crash. Inaddition, thrust ring 34, in cooperation with the notch of the upperrail, likewise works up the force that occurs upon forward or backwardacceleration.

[0044] It can moreover be seen from FIG. 9 that end stops 18 are formedby U-shaped brackets. Spindle 14 protrudes through the longitudinal armsof these U-shaped brackets, retaining shackles being provided at theends of these U-shaped brackets through which mounting rivets 16 areguided.

[0045] The device depicted in FIG. 1 to FIG. 3 is depicted in FIG. 4 asan end-on cross-sectional view of the seat rail. The referencecharacters already explained again stand for the known parts. It can beseen particularly clearly in the depiction of FIG. 4 that lower rail 10,which is U-shaped in cross section, has inwardly reflexed wall parts.Outwardly reflexed wall parts of upper rail 40 intrude between theseinwardly bent wall parts of lower rail 10, as viewed from the side wallsof upper rail 40. This making of upper rail 40 and lower rail 10 ensuresthat upper rail 40 and lower rail 10 cannot become laterally offset.Moreover, some guidance is provided.

[0046]FIG. 5 illustrates schematically the possible travel distancebetween the upper rail and the lower rail. In the present exemplaryembodiment, 343 mm is provided as a possible travel distance.

[0047]FIG. 6 shows particularly clearly, in cross-sectional view, theslotted bridges made in upper rail 40, which markedly constrict theinterior space in the U-shaped upper rail and thus serve as stop fortransmission 30.

[0048]FIG. 10 shows upper rail 40 and lower rail 10 together with theabove-described individual components in exploded view. The alreadyknown components are provided with the same reference characters asabove.

[0049] Transmission 30 is drawn in FIG. 11 with its housing bottom 32and housing top 31 together with box-shaped integrally molded elementsin the assembled condition. The stop lugs inwardly turned over from theupper wall of upper rail 40 can also be seen in this depiction.

[0050] Thrust ring 34 extending forth laterally from the housing oftransmission 30. FIG. 12, already explained, shows the transmission inan exploded view. Here spindle nut 36 together with worm gear andintegrally molded thrust ring 34 can be seen clearly. Worm 35, which isdriven by the flexible shaft, engages with worm gear 37. Thetransmission is moved along spindle 14 by this drive.

[0051] The transmission is once again clearly depicted without a housingin FIG. 13, the worm on flexible shaft 50 having been omitted forgreater clarity. Flexible shaft 50 is guided into the housing of thetransmission via flexible shaft adapter 52, already referred to. Abayonet connection 60 with grips 62 takes care of mounting the flexibleshaft to the housing of transmission 30 in a suitable manner. In FIG.16, once again, individual depictions, each in longitudinal section, areshown in order to make clear the accommodation of crash forces. Here itshould be remarked that notch 42 or relief in upper rails 40 in theregion of thrust ring 34 is formed such that there is no contact betweenthrust ring 34 and upper rail 40 in the normally installed condition.Only in the case of a crash does thrust ring 34 brace itself against thehousing wall of upper rail 40. As can be seen from FIG. 14, inparticular from the depiction at the top right, thrust ring 34 touchesupper rail 40 in the case of a crash with a contact surface that issegment-shaped at the left and right on thrust ring 34. Thus thrust ring34 braces itself symmetrically against the left side wall and the rightside wall of upper rail 40.

List of Reference Characters

[0052]10 Nut rail

[0053]11 Slotted bridge

[0054]11 Mounting screw

[0055]14 Spindle

[0056]16 Mounting rivet

[0057]18 End stop

[0058]20 Adjustment nut

[0059]22 Stop nut

[0060]30 Transmission

[0061]31 Housing top

[0062]32 Housing bottom

[0063]34 Thrust transmission

[0064]35 Worm

[0065]36 Spindle nut

[0066]37 Worm gear

[0067]38 Plain washer

[0068]40 Upper rail

[0069]41 Slotted bridge

[0070]42 Notch

[0071]43 Stop lug

[0072]45 Notch

[0073]46 Wall section

[0074]50 Flexible shaft

[0075]52 Flexible shaft adapter

1. Longitudinal seat adjustment device, especially in a motor vehicle,having a lower rail fixed to a chassis, inside which lower rail an upperrail to which a seat is attached can be propelled by motor, a spindlesitting inside the upper rail and having its respective ends fixed tothe lower rail, on which spindle a transmission fixedly coupled to theupper rail is arranged in axially movable fashion, characterized in thatthere are recesses in opposite side walls of the upper rail into which athrust ring, fixed to the spindle and sitting with its principal surfacetransverse to the longitudinal axis of the spindle, intrudes and ispressed against the side walls of the upper rail in the case of a crash.2. Longitudinal seat adjustment device, especially in a motor vehicle,having a lower rail fixed to a chassis, inside which lower rail an upperrail to which a seat is attached can be propelled by motor, a spindlesitting inside the upper rail and having its respective ends fixed tothe lower rail, on which spindle a transmission fixedly coupled to theupper rail is arranged in axially movable fashion, characterized in thatthe transmission is clampingly held in the upper rail and has atransmission housing whose opposite housing walls lie between wall partsof the upper rail and whose upper wall projects from the upper rail. 3.Device according to claim 1 or 2, characterized in that at least one ofthe wall parts of the upper rail has a notch through which a flexibleshaft coupled to a drive motor is guided.
 4. Device according to claim1, 2 or 3 characterized in that side walls of the upper rail wall parts(=“slotted bridges”) are pressed into the interior of the upper rail andin that the transmission housing brace itself against these slottedbridges.
 5. Device according to one of claims 1 to 4, characterized inthat the transmission housing has two housing shells made of plastic,which are connected to one another by ultrasonic welding.
 6. Deviceaccording to one of claims 1 to 5, characterized in that the clampingholding of the transmission by metal stirrups bent into an L-shape madeoppositely in a recess in the upper rail, between which stirrups thetransmission housing is slipped with wall tapers.
 7. Device according toone of claims 1 to 6, characterized in that the transmission has aspindle nut resting on the spindle with worm gear and a worm engagingwith the worm gear.
 8. Device according to claims 7, characterized inthat a thrust ring is integrally molded onto the spindle nut.
 9. Deviceaccording to claims 8, characterized in that the spindle nut and thethrust ring are made of metal.
 10. Device according to claims 8 or 9,characterized in that the worm gear is coaxially applied to the spindlenut by plastic injection.